The projects in progress involve (1) regulation of the synthesis and activity of ribosomes and RNA polymerase in the bacterium Escherichia coli and (2) molecular mechanisms of action of antibiotics which affect RNA and protein synthesis. The transcription of specific genes in the bacterium is being monitored using composite plasmid or transducing phage DNAs as specific probes in RNA-DNA hybridizaton assays. Synthesis of specific protein is being monitored by enzyme activity or electrophoresis of labeled cell extracts. The joint regulation of RNA polymerase and ribosomal proteins is being investigated by inhbiting RNA synthesis using transcription inhibitor antibiotics (i.e., rifampicin or streptolydigan) or a thermosensitive RNA polymerse initiation mutant. Partial inhibition of RNA transcription stimulates transcription of RNA polymerase subunit genes and at least some ribosomal protein genes but abolishes transcription of lactose utilization genes. The influence of gene amplification using plasmids carrying ribosomal proteins or RNA polymerase genes is also being investigated. In addition to this physiological analysis, nucleotide sequence analysis of the RNA polymerase and ribosomal protein gens and their regulatory sequence in the rif region of the chromosome is being determined.